1. Field of the Invention
This invention relates to testing geologic formations. More specifically, the invention relates to testing involving measuring a pressure of a formation and testing a sample of a formation fluid downhole.
2. Description of the Related Art
Exploration and production of hydrocarbons generally requires testing of geologic formations that may contain reservoirs of the hydrocarbons. Testing is performed to determine several parameters of the formation. One important parameter is formation pressure.
In a formation pressure test, a downhole tool extends a formation pressure test device to contact a wall of a borehole penetrating the formation. Pressure in the device is drawn down until formation fluid enters the device. The pressure at which the formation fluid enters the device is the formation pressure.
A low bandwidth communications system such as a pulsed-mud system is traditionally used to start the formation pressure test. In addition, the low bandwidth communication system is used to transmit a limited amount of data from the formation pressure test device to the surface of the earth for evaluation.
The time it takes for the data to be transmitted to the surface of the earth is generally greater than the time required for performing each step in the formation pressure test. Thus, once the test is started, then the test is brought to completion even if a problem develops during the test. Complications during the test can result in an improperly performed test producing poor quality data or no data at all. If a component of the formation pressure test device is damaged, then several complete cycles of testing may be performed before the component is identified as being damaged. Time lost performing inadequate tests in a borehole can be a waste of resources.
Therefore, what are needed are techniques for performing tests in a borehole and communicating test results to a remote location in a time short enough to enable control of the test during the test process.